Vinyl ester resin compositions containing dicyclopentadiene alkenoate

ABSTRACT

Thermosetting resin compositions containing vinyl ester resins having terminal unsaturation, vinyl aromatic monomers, and dicyclopentadiene alkenoate concentrates are useful to make fibrous reinforcement laminates. The use of the dicyclopentadiene alkenoate concentrate accelerates the rate at which hardness develops during room temperature cure.

BACKGROUND OF THE INVENTION

This invention relates to a thermosetting resin composition containingvinyl ester resins having terminal unsaturation, a vinyl aromaticmonomer, and a dicyclopentadiene alkenoate concentrate and laminatesprepared from them. More specifically, the invention relates tocompositions containing vinyl ester resins produced by reacting apolyepoxide resin with an ethylenically unsaturated monocarboxylic acidin about equivalent amounts. These vinyl ester resins are blended withvinyl aromatic monomers and a dicyclopentadiene acrylate concentrate toproduce a thermosetting resin composition or blend.

Vinyl ester resins having terminal unsaturation defined above, arecommercially available and well known from U.S. Pat. Nos. 3,367,992;3,564,074 and 3,594,247.

The above patents indicate a wide variety of unsaturated monomers thatcan be used to cure the above vinyl ester resins.

SUMMARY OF THE INVENTION

It now has been found that a thermosetting resin composition can beprepared using a vinyl ester resin having terminal unsaturation andabout 20 to about 70% by weight of an unsaturated monomer mixture of avinyl aromatic monomer and a dicyclopentadiene alkenoate concentrate. Anadvantage of this invention is that the use of a dicyclopentadienealkenoate concentrate accelerates the rate at which hardness developsduring the room temperature cure of the resins.

The thermosetting resin composition of this invention comprises

(A) about 80 to about 30% by weight of a vinyl ester resin havingterminal unsaturation,

(B) about 20 to about 70% by weight of an unsaturated monomer mixture ofa vinyl aromatic monomer and a dicyclopentadiene alkenoate concentratewherein the range of dicyclopentadiene alkenoate concentrate in saidmixture ranges from about 5 to about 90 weight percent.

A related aspect of this invention is a fibrous reinforcement laminatewhich has been impregnated and cured with the above composition.

The vinyl ester resin is blended with an ethylenically unsaturatedmonomer mixture copolymerizable with the resin. The mixture comprisesvinyl aromatic monomers such as styrene, methyl styrene, chlorostyrene,vinyl toluene, divinyl benzene or diallyl phthalate with about 5 toabout 90 weight percent of dicyclopentadiene alkenoate concentrate.

These vinyl ester blends with the unsaturated monomer mixture shouldcontain 20 to about 70 percent by weight and preferably 30 to 50 percentby weight of the monomer mixture based on the weight of the vinyl esterresin. A small amount of an inhibitor such as tertiary butyl catechol orthe like is added to this mixture. The amount added is not critical butis generally in the range from about 50-300 parts per million based onthe amount of unsaturated monomer.

The final blend is a crosslinkable vinyl ester composition which isuseful to make laminates, moldings, and coatings.

DETAILED DESCRIPTION OF THE INVENTION

The dicyclopentadiene alkenoate concentrates used herein are made by theacid catalyzed reaction of a commercial C₁₀ hydrocarbon streamcontaining at least 50% dicyclopentadiene with an alkenoic acid such asacrylic acid. The process is known from British Pat. No. 1,114,585.

While it is preferred to use acrylic acid in this process, othermonocarboxylic alkenoic acids having 3-5 carbon atoms can be used suchas methacrylic acid, crotonic acid, isocrotonic acid, angelic acid,tiglic acid, and mixtures thereof.

.[.The concentrates thus prepared consist mainly of

(a) about 50-100% by weight of compounds of the formula.]. ##STR1##.[.(b) about 0-30% of compounds of the formula.]. ##STR2## .[.(c) about0-2% of compounds of the formula.]. ##STR3## .[.and

(d) about 0-2% of compounds of the formula.]. ##STR4## .[.where R is aalkenyl group such as acrylyl, methacrylyl, crotonyl, etc. and R₁ ishydrogen or a methyl group..].

The vinyl ester resins having terminal unsaturation used herein areprepared by reacting an unsaturated monocarboxylic acid with apolyepoxide in about equivalent amounts, i.e., about one acid group perpolyepoxide group. The preparation of vinyl ester resins, catalysts forthe reaction, useful copolymerizable monomers, etc., are described innumerous patents. Typical of these patents is U.S. Pat. No. 3,377,406which describes certain onium catalysts which may be used to prepare thevinyl ester resins herein and which has an extensive disclosure as totypes of polyepoxides, unsaturated acids, etc. Other patents whichillustrate the state of the art are U.S. Pat. Nos. 3,179,623; 3,301,743;and 3,256,226.

Briefly, any of the known polyepoxides may be used and include glycidylpolyethers of polyhydric phenols and polyhydric alcohols, epoxy novolacsand the like. Preferred polyepoxides are the bisphenol-based resins andepoxy novolacs which have epoxide equivalent weights of about 150 to1000. Unsaturated acids include acrylic and methacrylic acids and theirvarious substituted derivatives, cinnamic acid and the like. Alsoincluded are the dicarboxylic acid half esters of hydroxyalkyl acrylatesas taught in U.S. Pat. No. 3,367,992.

Also included in the definition of the vinyl ester resins used hereinare the modified resins in which the resin is post reacted with adicarboxylic acid anhydride to form pendant half ester groups. Resins ofthis type are described in U.S. Pat. No. 3,564,074. The resins may alsobe modified by reaction with isocyanates, other anhydrides, and otherreagents reactive with the hydroxyl group produced from the acid/epoxideprimary resin-forming reaction. These modification reactions includereaction with up to all of the hydroxy groups present in the vinyl esterresin.

The laminates of this invention are made by mixing into thecrosslinkable composition free radical forming catalysts in knownamounts and adding this mixture to a suitable fibrous reinforcement suchas asbestos fibers, carbon fibers, fibrous glass; or inorganic fibers.Examples of these catalysts are benzoyl peroxide, tertiary butylperoxide, methylethyl ketone peroxide and the like. It is frequently ofvalue to add accelerators such as cobalt naphthenate, dimethyl aniline,and the like.

The vinyl ester is rolled, sprayed or impregnated into the fibrousreinforcement such as fibrous glass and cured in a manner well known inthe art. When fiberous glass is used, it can be in any form such aschopped strands, filaments, glass ribbons, glass yarns, or reinforcingmats.

The following examples are presented to illustrate but not limit theinvention.

EXAMPLES 1 AND 2

A commercial vinyl ester resin was blended with various amounts ofstyrene and dicyclopentadiene acrylate concentrate. The systemsevaluated are described in Table I. The vinyl ester resin used was thereaction product of about 9 weight percent methacrylic acid and apolyepoxide which has been prepared by reacting about 3 parts of thediglycidyl ether of bisphenol A with 1 part bisphenol A after whichabout 1.25 parts by weight of the diglycidyl ether of bisphenol A isblended therewith. The acid/epoxide reaction product is then reactedwith about 0.2 part by weight of maleic anhydride.

                  TABLE I                                                         ______________________________________                                        RESIN PROPERTIES                                                              percent vinyl  percent  percent  ppm Inhibitor                                System  ester resin                                                                              Styrene  DCPD-A MeHQ  TBC                                  ______________________________________                                        Control A                                                                             55         45       0      100   12                                   Example 1                                                                             55         36       9      100   10                                   Example 2                                                                             55         27       18     100    7                                   ______________________________________                                                        180° F. SPI Gel Time                                           min.     Room     min.                                                        22° C.                                                                          Temp.    Gel  min.    Maximum                                System  Viscosity                                                                              Gel Time Time Cure Time                                                                             Exotherm                               ______________________________________                                        Control A                                                                              468 cps 17.7     7.4  9.4     398° F.                         Example 1                                                                              890 cps 17.7     6.4  8.3     393° F.                         Example 2                                                                             1932 cps 21.0     8.3  8.8     376° F.                         ______________________________________                                         MeHQ is methyl hydroquinone                                                   TBC is ptertiary butyl catechol                                               DCPDA is dicyclopentadiene acrylate made from the reaction of one mole of     acrylic acid with one mole of dicyclopentadiene concentrate in the            presence of BF.sub.3 as the catalyst                                     

EXAMPLES 3 AND 4

Glass laminates, containing 25% random fiber glass mat, were preparedusing the resin blends in Table I. Two fiber glass plys and a normalhand-roller technique were used to make a part about 1/8-inch thick and12 inches by 14 inches in dimensions for each resin blend. Table IIdescribed the catalysts used with the resin blends so that the gel timewould be about 15 to 18 minutes.

                  TABLE II                                                        ______________________________________                                        CATALYST SYSTEM                                                                       Percent               Per-  Room Temp.                                        Lupersol Percent Cobalt                                                                             cent  Gel Time                                  System  DDM® Naphthenate 6%                                                                             DMA   (minutes)                                 ______________________________________                                        Control B                                                                             1.0      0.1          0.1   17.7                                      (Control                                                                      A blend)                                                                      Example 3                                                                             1.0      0.1          0.1   17.7                                      (Example                                                                      1 blend)                                                                      Example 4                                                                             1.2      0.1          0.1   18.4                                      (Example                                                                      2 blend)                                                                      ______________________________________                                         Lupersol DDM® is methylethyl ketone peroxide                              DMA is dimethylaniline                                                   

The hardness development data is shown in Table III wherein it showsthat the hardness development is much more rapid for Examples 3 and 4and is significantly higher.

                  TABLE III                                                       ______________________________________                                        HARDNESS DEVELOPMENT                                                                    Control D   Example 3   Example 4                                   Time      B           B           B                                           ______________________________________                                        45    min.    --          30        16                                        1     hr.      7          32        21                                        2     hrs.    14          31        26                                        3     hrs.    16          32        27                                        4     hrs.    18          32        31                                        5     hrs.    20          33        30                                        6     hrs.    21          32        29                                        7     hrs.    22          33        31                                        8     hrs.    23          32        32                                        24    hrs.    26          33        35                                        ______________________________________                                         B is Barcol Hardness                                                     

Heat distortion measurements by ASTM-D648-56 are as follows:

                  TABLE IV                                                        ______________________________________                                               Resin         HDT °C.                                           ______________________________________                                               Control       81                                                              Example 1     80                                                              Example 2     84.5                                                     ______________________________________                                    

Table IV shows that DCPD-A effectively takes part in the crosslinkingreaction with styrene and the unsaturation of the vinyl ester. A usefulproduct has been obtained.

I claim:
 1. A thermosetting resin composition which comprises(A) about80 to about 30% by weight of a vinyl ester resin having terminalunsaturation, (B) about 20 to about 70% by weight of an unsaturatedmonomer mixture of a vinyl aromatic monomer and dicyclopentadienealkenoate concentrate .[.comprising (a) about 50-100% by weight ofcompounds of the formula.]. ##STR5## .[.(b) about 0-30% of compounds ofthe formula.]. ##STR6## .[.(c) about 0-2% of compounds of the formula.].##STR7## .[.and (d) about 0-2% of compounds of the formula.]. ##STR8##.[.where R is a alkenyl group having 2-4 carbon atoms and R₁ is hydrogenor a methyl group.]. wherein the range of dicyclopentadiene alkenoateconcentrate in said mixture ranges from about 5 to about 90 weightpercent.
 2. The resin composition of claim 1 wherein the vinyl esterresin is prepared by the reaction of about equivalent proportions ofpolyepoxides, with ethylenically unsaturated monocarboxylic acids,2-hydroxyalkyl acrylate half esters of dicarboxylic acids, or mixturesof same with or without the subsequent reaction of dicarboxylic acidanhydrides with the epoxide-unsaturated monocarboxylic acid reactionproduct.
 3. The resin composition of claim 1 wherein thedicyclopentadiene alkenoate concentrate is dicyclopentadiene acrylate.4. A cured fibrous laminate made with the composition of claim
 1. 5. Acured fibrous laminate made with the composition of claim
 2. 6. A curedfibrous laminate made with the composition of claim
 3. 7. A cured glassfiber laminate made with the composition of claim
 1. 8. A cured glassfiber laminate made with the composition of claim
 2. 9. A cured glassfiber laminate made with the composition of claim 3.